In an integrated circuit it may be desirable, depending on the application, for the integrated circuit to have an energy-saving mode. Besides the requirement that as much energy as possible is intended to be saved with such an energy-saving mode, other requirements may also be made of an energy-saving mode, such as, for example, a rapid return from the energy-saving mode to normal operation, for example normal data processing operation, a rapid entry to the energy-saving mode and a low current consumption during the transitions to the energy-saving mode and back to normal operation. It is desirable to provide circuits which meet such requirements.